Geriatrics / Gériatrie Delirium in the Elderly

There are many references to delirium in the extant works of Hippocrates and thus its history goes back almost 2,500 years. Greek and Roman writers recognized three main forms of mental disorders: mania, melancholia, and phrenitis or delirium. Aretaeus, a second century Roman writer, classified diseases as acute or chronic, and phrenitis and lethargy (lethargus) were the chief acute mental disorders. While phrenitis typically involved restlessness, insomnia, and hallucinations, lethargy involved undue quietness and sleepiness. Both were believed to be caused by fever or poisons. Their treatment included both a physiological and a psychological approach [1]. The word delirium is derived from the Latin term for “off the track.” The term “delirium” was first used by Cornelius Celsus in the first century A.D., but on the whole the word “phrenitis” was used more often in the ancient medical literature. The first description of delirium in the English medical literature appeared in Barrough’s textbook The Method of Physick, first published in 1583 (Barrough, 1583). He referred to it as “frenesie” and observed that it involved the derangement of four main functions: imagination, cogitation, memory, and reason. It also featured disturbed sleep [2]. Though the core clinical features of delirium were already spelled out in the sixteenth century, diagnostic criteria have continued to evolve. The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), due out in May 2013, will likely define delirium as a disturbance in the level of awareness or attention (rather than consciousness as in the previous edition), marked by the acute or subacute onset of cognitive changes attributable to a general medical condition. It tends to have a fluctuating course and must not be solely attributable to another cognitive disorder, although delirium is common in the setting of major neurocognitive disorders [3]. DSM-V may also subcategorize delirium into hyperactive, hypoactive, and mixed varieties [4]. Patients with hyperactive subtype of delirium are typically agitated and restless. Hypoactive patients have decreased level of consciousness and psychomotor retardation. Patients with mixed subtype have features of both.